We got some water coming into one of our walls after a recent prolonged snowmelt (lots of snow, slowish melt down). I'm about 99% sure that the source of the water is the supports for a cantilevered balcony. The supports are continuations of the interior framing, so they are an intrusion through the wall. I think some water gets on top of the supports and runs along them, either due to a slight backward slope or capillary effect. To check that hypothesis I put a bucket of water with some holes in it on the balcony to simulate a snowmelt, and 5 minutes later I saw a trickle of water coming down the sheathing and framing below.
The builder did put in flashing between the decking and the supports, but it only extends about 4" from the wall. They also caulked around the supports, but it's not the most thorough job ever, nor is it easy to do a more thorough job due to the decking getting in the way.
I've come up with a few possible solutions, but I'm not wildly enthusiastic about any of them, so I thought I'd see if anyone else has any great ideas.
I should probably mention that this is in Denver, so we occasionally get some decent rain, snow and wind, but not Gulf Coast-style hurricane craziness.
Ideas I've seen so far:
- Install a waterproof decking system. I don't like this because it seems like overkill - there is nothing below the balcony that needs to be protected from water, I just need to keep it out of the house. Also I suspect it would be too tall for the door threshold.
- Cut a kerf (very small channel) into each support below the flashing, to allow water to escape. Seems straightforward, but cutting structural supports, even just a little, makes me nervous.
- Put a line of silicone caulk around each support to break the path. Seems easy, though I wonder how long before the caulk breaks down.
- A system of flashing and membranes around the supports. Seems complicated and difficult to install. The examples I saw used custom fabricated flashing.
Anyone have ideas for how to handle that? Like or dislike any of the above?
